Our results of bone grafting to the alveolar process during the mixed dentition were investigated in 55 consecutively treated patients (66 clefts). The amount of remaining bone and gingival retraction at the tooth mesial to the cleft after 3 and 12 months was measured and correlated with the following anatomical conditions present during surgery: width of the cleft, rotation of the adjacent incisor, stage of eruption of the tooth distal to the cleft. It was also considered if any deciduous lateral incisor or canine was extracted during surgery and if any flap dehiscence took place postoperatively. It was found that flap dehiscence resulted in significantly less bone at 3 months and at 1 year after surgery. Furthermore, extraction of a deciduous tooth was found to be significantly correlated to less bone 1 year after surgery, in which cases there were also persisting gingival retractions. The other factors had no significant influence on the outcome of surgery.